<body>
  <div id="container"></div>
  <script>
    function createCalendar(ele, year = 1990, month = 1) {
      let table = document.createElement("table");
      let weekWords = ["MO", "TU", "WE", "TH", "FR", "SA", "SU"];
      let head = document.createElement("th");
      table.append(head);
      ele.append(table);
      for (let w of weekWords) {
        let cell = document.createElement("td");
        head.append(cell);
        cell.textContent = w;
      }
      let d = new Date(year, month - 1);

      
    }
    createCalendar(container);
  </script>
</body>
